(2) Apply anodize.
NOTE: This process is for low-stressed aluminum-alloys where a hard wear-resistant coating with corrosion resistance is required and where the loss of fatigue strength, tensile strength, and elongation will not adversely affect service.
(a) Apply anodize in accordance with AMS2469 or MIL-A-8625 to the type and class specified in applicable manual for unit being worked.
NOTE: Hard anodize coatings are divided into types and classes. Type designates color and class designates thickness. Type I will vary from a natural metallic color to brown or dark gray according to alloys and thickness.
Type I Natural Anodized Color
Class A 0.0002 to 0.0004 inch (0,00508 to 0,01016 mm)
Class B 0.0004 to 0.0008 inch (0,0106 to 0,02032 mm)
Class C 0.0010 to 0.0020 inch (0,0254 to 0,00508 mm)
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Class D 0.0001 to 0.0002 inch (0,00254 to 0,00508 mm)
Type II Dyed Black Color
Class A 0.0002 to 0.0004 inch (wrought material only) (0,00508 to 0,01016 mm)
Class B 0.0004 to 0.0008 inch (0,0106 to 0,02032 mm)
Class C 0.0010 to 0.0020 inch (0,0254 to 0,00508 mm)
B. Method No. 403B: Hard Chrome Plated Parts Repair
NOTE: Hard chrome plating is used primarily on steel parts for the purpose of increasing abrasion resistance to reduce wear and friction between sliding surfaces. It is also used to recondition worn or over machined areas as a salvage repair.
Hard chrome plating is usually relatively thick, ranging from 0.002 to 0.010 inch (0,0508 to 0,254 mm), and is applied directly to the base metal.
Repair hard chrome plated parts as follows:
WARNING: USE CORRECT PERSONAL PROTECTION. PROCEDURES THAT NEED GRIND/MACHINE WORK WILL CAUSE LOOSE PARTICLES THAT CAN GET IN YOUR EYES.
(1)
Machine surface as required to ensure a 0.002inch (0,0508 mm) minimum thickness of chrome plating after final matching.
(2)
Perform magnetic particle or fluorescent penetrant inspection as applicable. Refer to SECTION III.
(3)
Degrease part in accordance with SECTION II.
(4)
Mask area of part not to be chrome plated.
(5)
Apply hard chrome plate in accordance with Federal Specification QQ-C-320B.
WARNING: USE CORRECT PERSONAL PROTECTION. PROCEDURES THAT NEED GRIND/MACHINE WORK WILL CAUSE LOOSE PARTICLES THAT CAN GET IN YOUR EYES.
(6)
Machine surface to dimensions and surface finish specified in applicable manual.
(7)
Perform reverse plating for improved wear properties after grinding or honing. No measurable dimensional change is allowable. For Class A, chrome plate, reverse after eight to twelve seconds in the plating bath with the same fixture used and at the same density.
(8)
Deburr reworked area and remove over-spray. Remove masking tape.
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C. Method No. 403C: Thin Dense Chrome Plated Parts Repair
Repair thin dense chrome plated parts as follows:
NOTE: The following instructions are primarily for the application of a thin chromium coating on low-alloy steels and corrosion-resistant alloys to increase wear resistance.
1.
Thickness requirements shall be as specified in applicable manual, but shall not exceed 0.0005 inch (0,0127 mm) thick.
2.
When plating thickness is not specified, coating shall be 0.0001 to 0.0002 inch thick.
3.
Plating 0.0001 to 0.0002 inch (0,00254 to 0,00508 mm) thick will provide wear protection for alloys with a hardness of over Rockwell C40, and a plating thickness of 0.0002 to 0.0005 inch (0,00254 to 0,00508 mm) will protect alloys with a hardness less than Rockwell C40.
(1) Prepare surfaces.
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